The primary objective of this project is to prospectively examine and define the epidemiology of HIV-1 and HIV-2 in a region of Western India, where both viruses have been identified with increasing prevalence over the last 3-5 years. Most of the information about HIV infection in Asia has been initiated, and only recently, have studies of HIV infection in India been initiated. Preliminary studies of HIV in India suggest a 20% seroprevalence rate in high risk groups of commercial sex workers and 5-10% in STD clinic attendees. The prevalence in blood donor has recently been reported to be 3/1000 and a few reports suggest that up to 10% of infection is due to HIV-2. To date, there have been no prospective studies to define the incidence of HIV-1 or HIV-2 infection in India. Therefore, we propose to study both HIV-1 and HIV-2 infection in Pune, India, a city of 2 million people located 200 kilometers southeast of Bombay. The project site will be the National Institute of Virology (NIV), the AIDS reference center for the Indian Council of Medical Research. The purpose of the study will be to define the incidence of HIV-1 and HIV-2 in two high risk groups, commercial sex workers and STD patients. The study will attempt to identify and characterize the biological and behavioral cofactors associated with the risk of acquisition HIV-1 and HIV-2 in these groups. Specimens will be collected from HIV positive individuals to investigate the distribution of genetic and antigenetic HIV variance in India. The long-term objective of this project is to strengthen the infrastructure and field management capacity of the National Institutes of Virology for future HIV vaccine efficacy trials. We plan to screen 3,000-4,000 high risk individuals from an STD clinic presently located at the Sasoon Hospital, and from two sites in the "red light" district of Pune. Extensive follow-up of seronegative participants will occur every three months for two years to determine the seroincidence of HIV-1 and HIV-2, including detailed interviews to evaluate behavioral risks associated with transmission. In addition, this proposal calls for the establishment of a fully-equipped microbiological laboratory in Pune for investigations of STDs that may be biological cofactors associated with HIV transmission in this cohort. This project will establish, through technology transfer and collaborations with Johns Hopkins University, and HIV-based infrastructure for self-directed and self-sufficient HIV vaccine research in the future.